Why do people vote?

I am, admittedly, a presidential election junkie. I tune in to the debates, listen to the pundits and their projections and watch the returns roll in until every state is colored in red or blue. But I doubt that I would enjoy the process so much if I didn't vote. Once I punch my ballot and put on my "I Voted" sticker, a slight weight is lifted from my shoulders knowing that I've done everything in my democratic power to bring my desired candidate into office. But why do I feel like such a saint when my vote only has a 1 in 60 million chance of making an actual difference in a presidential election? From researching that very question, it turns out that voting is a product of sociocultural, biological and psychological factors that are far more complex than the simple act of pulling a lever or checking a box. Some people are literally hardwired to show up at polling stations, whereas others unapologetically abstain. Either way, it's incredible that for all of the time, effort and money poured into the American voting system, it remains one of the most irrational habits we maintain.

Sources

Blais, Andre and Rheault, Ludovic. "Optimists and skeptics: Why do people believe in the value of their single vote?" Electoral Studies. Vol. 30, Issue 01. March 2011. (June 13, 2012) http://www.sciencedirect.com/science/article/pii/S0261379410000971

Gelman, Andrew; Silver, Nate; and Edlin, Aaron. "What is the probability your vote will make a difference?" National Bureau of Economic Research. August 2009. (June 13, 2012) http://www.nber.org/papers/w15220.pdf